Carotid bodies contribute to sympathoexcitation induced by acute salt overload

Author(s)

da Silva, Elaine Fernanda ^[1] ; Bassi, Mirian ^[1] ; Menani, Jose Vanderlei ^[1] ; Almeida Colombari, Debora Simoes ^[1] ; Zoccal, Daniel Breseghello ^[1] ; Pedrino, Gustavo Rodrigues ^[2] ; Colombari, Eduardo ^[1]

Affiliation

^[1] Sao Paulo State Univ UNESP, Sch Dent, Dept Physiol & Pathol, Rua Humaita 1680, Araraquara, SP - Brazil

^[2] Univ Fed Goias, Biol Sci Inst, Dept Physiol Sci, Goiania, Go - Brazil

• Document type: Journal article
• Source: Experimental Physiology; v. 104, n. 1, p. 15-27, JAN 2019.
• Web of Science Citations: 0

Abstract

Acute salt excess activates central osmoreceptors, which trigger an increase in sympathetic and respiratory activity. The carotid bodies also respond to hyperosmolality of the extracellular compartment, but their contribution to the sympathoexcitatory and ventilatory responses to NaCl overload remains unknown. To evaluate their contribution to acute NaCl overload, we recorded thoracic sympathetic (tSNA), phrenic (PNA) and carotid sinus nerve activities in decorticate in situ preparations of male Holtzman rats (60-100 g) while delivering intra-arterial infusions of hyperosmotic NaCl (0.17, 0.3, 0.7, 1.5 and 2.0 mol l(-1); 200 mu l infusion over 25-30 s, with a 10 min time interval between solutions) or mannitol (0.3, 0.5, 1.0, 2.7 and 3.8 mol l(-1)) progressively. The cumulative infusions of hyperosmotic NaCl increased the perfusate osmolality to 341 +/- 5 mosmol (kg water)(-1) and elicited an immediate increase in PNA and tSNA (n = 6, P < 0.05) in sham-denervated rats. Carotid body removal attenuated sympathoexcitation (n = 5, P < 0.05) but did not affect the tachypnoeic response. A precollicular transection disconnecting the hypothalamus abolished the sympathoexcitatory and tachypnoeic responses to NaCl overload (n = 6, P < 0.05). Equi-osmolar infusions of mannitol did not alter the PNA and tSNA in sham-denervated rats (n = 5). Sodium chloride infusions increased carotid sinus nerve activity (n = 10, P < 0.05), whereas mannitol produced negligible changes (n = 5). The results indicate that carotid bodies are activated by acute NaCl overload, but not by mannitol. We conclude that the carotid bodies contribute to the increased sympathetic activity during acute NaCl overload, whereas the ventilatory response is mainly mediated by hypothalamic mechanisms. (AU)

• FAPESP's process: 11/50770-1 - Neural mechanisms involved of hydroelectrolytic balance and cardiorespiratory control
• Grantee: José Vanderlei Menani
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/17251-6 - Neural mechanisms generating the respiratory pattern and the respiratory-sympathetic coupling in conditions of hypoxia
• Grantee: Daniel Breseghello Zoccal
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 15/23467-7 - Experimental pathophysiology: role of central mechanisms of the cardiovascular and respiratory control changes induced by experimental hypertension and obesity
• Grantee: Eduardo Colombari
• Support Opportunities: Research Projects - Thematic Grants